地基膨胀土浸水膨胀变形试验研究

Experimental study on inundation swelling deformation of expansive soil foundation

以兰新铁路第二双线一处典型地基原状膨胀土为对象,分别进行0 k Pa、10 k Pa、20 k Pa、30k Pa、40 k Pa、50 k Pa分级浸水膨胀变形试验。试验结果表明:膨胀量随土体吸水量增加呈缓慢增长、加速增长、稳定增长的"S"形增长趋势。上覆荷载对膨胀量起抑制作用,且荷载越大,膨胀量越小,故膨胀土地基的膨胀变形主要发生在浅层膨胀土;胀限含水率随上覆荷载增大在逐渐减小,呈指数变化规律。通过对试验数据的进一步分析,建立了吸水率和上覆荷载耦合下原状膨胀土膨胀量计算模式。该计算模式所获结果与实测数据吻合较好,可为今后膨胀土地区工程建设提供一定的理论支撑。

By taking the undisturbed expansive soil at a location of the second double line of Lanzhou-Xinjiang Railways the ob-ject,the experiments on the graded inundation swelling deformations under the overlying loads of 0 kPa,10 kPa,20 kPa,30 kPa,40 kPa and 50 kPa are respectively made.The study result shows that along with the increase of the water absorption of soil mass,the swelling amount exhibits an“S”typed increasing trend of slow increase,accelerated increase and stable increase.The overlying load plays the restrictive role on the swelling amount,i.e.the larger the load is,the less the swelling amount is to be,thus the swelling deformation of the expansive soil foundation mainly occurs in shallow expansive soil,while the swelling limit wa-ter content is gradually decreased along with the increase of the overlying load with an exponential change law.Through the fur-ther analysis on the experimental data,the calculating mode of the swelling amount of the undisturbed expansive soil under the condition of the coupling of water absorption rate and the overlying load is established.The results obtained from the calculating mode are better coincided with the measured data,and then can provide a certain theoretical support for the construction of the project within the expansive soil region in the days to come.